Background Potentially modifiable parenting practices relating to mealtime environment and bedroom TV are implicated in the development of overweight and obesity, although it is unknown whether they shape different childhood trajectories of body mass index (BMI), overweight or obesity. The aims of this study were to (1) examine variation in trajectories of overweight among a representative sample of Scottish children; and (2) explore associations with mealtime social interaction and setting, and bedroom TV.

Methods We used the Growing Up in Scotland first birth cohort (baseline in 2004/5, child aged 10 months, n=5217), selecting families with a singleton birth, with mothers interviewed throughout and with child BMI measurement at 46, 70, 94 and/or 122 months (n=2,584). Growth mixture modelling (Mplus version 8) identified different trajectories in the likelihood of being overweight (≥85th BMI percentile, based on UK growth charts). Multinomial regression models (Stata version 14.2) explored whether informal mealtime setting (away from a dining area, mealtime screen use), positive mealtime interaction (‘enjoyable’, ‘time to talk’), and bedroom TV were associated with overweight trajectories, adjusting for child gender and birthweight and potential confounders (diet quality, permissive feeding, mealtime rules and screen time; maternal BMI; and baseline measures of family socio-economic status, smoking in pregnancy, breastfeeding, and timing of solid feeding).

Results Four overweight trajectories were identified, with sample percentage and probability of being overweight at 46 and 122 months as follows: Low (58%, 0.00, 0.10), High (13%, 1.00, 0.93), Increasing (19%, 0.31, 0.84) and Decreasing (10%, 0.82, 0.00). In fully adjusted models, High and Increasing trajectories were more likely than the Low trajectory to have positive mealtime interaction (respective relative risk ratios RRRs with 95% confidence intervals 1.30 (1.11–1.52), 1.26 (1.08–1.47)); and more likely to have a bedroom TV (1.97 (1.40–2.78), 1.48 (1.06–2.05)). Compared to the Low trajectory, the High trajectory also had a more informal mealtime setting (1.25 (1.09–1.44)). None of the parenting practices distinguished Decreasing from Low or Increasing trajectories. However, compared to the High trajectory, children in the Decreasing trajectory were less likely to have a bedroom TV, informal mealtime setting and positive mealtime interaction: RRRs respectively 0.55 (0.35–0.89), 0.75 (0.63–0.90), 0.74 (0.60–0.91).

Conclusion Potentially modifiable parenting practices were associated with different trajectories of child overweight. Findings challenge, while not explaining, the role of positive family mealtime interaction in parental management of child overweight, and support likely benefits of reducing screen use at mealtimes and in bedrooms.